The present invention relates to surgical clips for occluding bodily ducts, and, in particular to clips for performing sexual sterilization.
It is known to sterilize females by surgically applying clips to the Fallopian tubes. The clips have two jaws which are closed on a tube, thereby occluding the tube to prevent gametes passing. An individual is rendered sterile by clipping both tubes. The use of clips allows the process to be reversed in many cases, if required, by cutting out the devitalised length of tube and rejoining the remaining vital portions. Clips are known which devitalise a length of tube of only a few millimeters.
A design of clip must satisfy various medical requirements if it is to be successful. The following are among the most important of these requirements.
Firstly, the clip must overcome the tendency of the Fallopian tube to escape from the clip during the application process.
A second requirement is that application of the clip be atraumatic, that is rupture of blood vessels in the mesosalpinx is avoided. The mesosalpinx is a sheet of tissue containing blood vessels for supplying the Fallopian tube, which runs along one edge of the sheet. Rupturing of the mesosalpinx blood vessels, causing bleeding, could occur either as a result of a flaw in the design of the clip, or as a result of insufficiently careful application.
Finally, the clip must meet the normal medical requirements of non-toxicity and should also be effective against recanalization (re-opening) of the Fallopian tube after the clip has been applied.
A principle cause of recanalization is necrosis of the muscular tissue surrounding the lumen of the Fallopian tube. As necrosis occurs, the thickness of this tissue may decrease, so allowing the lumen to expand and reopen, and allowing gametes to pass once more along the lumen. Recanalization caused by the clip falling off after application must also be prevented.
Various clips have been proposed which incorporate catch mechanisms for holding the clips in place after application, or means for holding the tube between the jaws during application. These involve some traumatic danger of rupturing and bleeding. In some, relatively sharp edges come into contact with the mesosalpinx. In another, a spike engages the tube as the jaws close, and there is a significant risk of blood vessels being punctured.
There exists a need for a surgical clip which can be used relatively easily, quickly and safely to perform sexual sterilizations with reduced risk of bleeding, and which will remain securely in position after application. Moreover, there is a need for a clip which is amenable to relatively cheap mass production for supply to, for instance, the so-called Third World.